An automotive air-conditioning system normally adjusts the temperature by using an air mix door. The air mix door, with which the quantity of air to be supplied to the heater core and the quantity of air to bypass the heater core are adjusted, is a single-point fulcrum door and the air quantity ratio is adjusted by altering the degree of openness of the door. In recent years, the use of so-called sliding doors, which are opened/closed as they slide linearly has become increasingly common as an alternative to the single-point fulcrum door, since the sliding door does not take up as much space.
For instance, patent reference literature 1 discloses a sliding door structure having a sliding door loosely fitted in guide grooves by setting the width of the sliding door slightly smaller than the distance between the guide grooves so as to assure good slidability.
Patent reference literature 2 discloses a structure of a sliding door (an air mix damper 6) constituted with a flat rectangular plate with a small thickness and racks 100 that extend along the sliding direction formed near each of the two side edges of the sliding door. The two side edges of the sliding door are inserted at guide grooves 26. The structure is characterized in that a pinion 101 interlocks with the air mix damper 6 so that the rotational force of a rotating shaft 102 causes the air mix damper 6 to move reciprocally.
The structure disclosed in patent reference literature 2 includes a heat reflecting surface 106 formed at the air mix damper 6 at a position further toward a heater 5 in order to assure dependable slidability of the air mix damper by preventing thermal deformation thereof that might otherwise be caused by heat radiated from the heater 5.
Patent reference literature 3 discloses a structure adopted in a sliding door 15 constituted with a flat rectangular plate, which is thin and flexible, with racks 16a and 16b extending along the longitudinal direction each formed near one of the two ends of the sliding door along the lateral direction and the two ends of the sliding door inserted at guide grooves 11a and 11b. The sliding door 15 is pressed against seat surfaces 10a, 10b and 10c via elastic members 19. The sliding door 15 is caused to move reciprocally by the rotational force imparted from a drive shaft 22, via pinions 21a and 21b interlocking with the racks 16a and 16b at the sliding door 15.
The structure disclosed in patent reference literature 3 requires the position at which the drive shaft and the sliding door are made to interlock with each other and the assembly direction along which the drive shaft and the sliding door are assembled together during the assembly of the air-conditioning unit to be set accurately, since the drive shaft and an external actuator used to rotate the drive shaft must achieve an optimal match.
Accordingly, the applicant of the present invention already proposed an invention that includes both an alignment function for ensuring that the sliding door and a shaft used to drive the sliding door are assembled together at an optimal position during the assembly of an air-conditioning unit and a temporary hold function which is engaged to temporarily hold the shaft to the sliding door (Japanese Patent Application No. 2002-379903).
The structure according to the invention disclosed in the above publication includes a pair of male engaging portions 26 projecting out from the shaft 15, a pair of female engaging portions 28 formed at the sliding door 23, a passing hole 29 at the shaft 15 and a hole 31 formed at the door main unit 15 at the surface on which racks 24 are formed. As pinions 17 at the shaft 15 become interlocked with the racks 24 and the pair of male engaging portions 26 and the pair of female engaging portions 28 become engaged with each other, positional alignment is achieved. Then, by aligning passing holes 29 with holes 31 and then inserting a jig 34 through the holes, the shaft becomes temporarily held onto the sliding door.
Patent reference literature 1 mentioned earlier also discloses a sliding door device having a sliding door that slides along a direction that intersects the air flow path. This sliding door device is characterized in that a sliding air mix door is disposed between the evaporator and the heater core, that a seal member is bonded onto the door main unit of the air mix door and that as the door main unit is caused to move along the direction intersecting the sliding direction at the sliding end position, the seal member is pressed against a contact portion formed at the case.
The primary object of the structure described above is an improvement in the quality of the seal achieved by moving the sliding door along the direction intersecting the sliding direction as the sliding door having moved through the guide grooves reaches the sliding end position and thus pressing the seal member against the contact portion formed at the air-conditioner case.
There is another structure known in the related art disclosed in patent reference literature 4 and adopted in a sliding door device that switches the air flow path in order to adjust the ratio of the quantity of air to pass through the heat exchanger used for heating in the air-conditioning unit and the quantity of air to bypass the heating heat exchanger. This structure includes racks formed at the sliding door and pinions disposed at the shaft, which are made to interlock with each other and, as the rotational movement of the shaft is communicated to the sliding door, the sliding door is caused to slide along the direction intersecting the direction of the air flow. However, the problem of dirt, dust and the like in the air taken in through the inside air/outside air intake ports entering the space between the rack at the sliding door and the pinion at the shaft to result in resistance against the movement of the sliding door or unpleasant noise during the sliding door operation is not addressed in the sliding door device for an air-conditioning system disclosed in patent reference literature 4.
Patent reference literature 5 discloses a structure that includes flexible sliding contact pieces disposed at a frontward position and a rearward position along the direction in which the roller unit advances. As the sliding door moves, the sliding contact pieces dispel any dirt, dust or the like from the guide surface of the rails, thereby preventing dirt, dust or the like from building up on the rails supporting the sliding door.
The single-point fulcrum doors in the related art include those adopting a structure in which the air mix door (plate door) is driven via a cable as disclosed in patent reference literature 6. The structure is adopted in a door drive device to prevent transmission of any force attributable to the deadweight of the plate door or the air pressure or the like to which the door is subjected, from the door side to the operation unit. The structure includes the air mix door 4 mounted so as to constitute an integrated unit together with a door shaft 41, a worm wheel 43 fixed onto the door shaft 41, a worm gear 441 at the shaft 44 made to interlock with a gear 434 at the worm wheel 4, a bevel gear 442 disposed at the shaft 44 and a spur wheel 450 made to interlock with the bevel gear 442. The spur gear 450 is formed at a plate 45 connected to a cable 47. The advisability of adopting this mechanism in conjunction with a sliding door is questionable.
Moreover, patent reference literature 7 discloses a structure adopted in a sliding door device that switches the air flow path in order to adjust the ratio of the quantity of air to pass through a heating heat exchanger in the air-conditioning unit and the quantity of air to bypass the heating heat exchanger, which includes racks disposed at the door main unit and pinions disposed at the shaft made to interlock with each other so as to slide the door main unit along a direction intersecting the direction of the air flow by transmitting the rotational movement of the shaft to the sliding door. The shaft in the sliding door device disclosed in the publication has a diameter, measured at a bridge portion disposed between the pinions, set to a relatively small value compared to the diameter at the cylindrical portion at the two ends thereof in order to minimize the air flow pressure.
Patent reference literature 1: Japanese Unexamined Patent Publication No. H10-278544
Patent reference literature 2: Japanese Unexamined Patent Publication No. H10-297246
Patent reference literature 3: Japanese Unexamined Patent Publication No. 2003-104032
Patent reference literature 4: Japanese Unexamined Patent Publication No. H11-20454
Patent reference literature 5: Japanese Unexamined Patent Publication No. H9-317305
Patent reference literature 6: Japanese Unexamined Patent Publication No. 2000-203242
Patent reference literature 7: Japanese Unexamined Patent Publication No. 2001-113936